Embodiments of the present invention relate to a semiconductor device and a method for manufacturing the same.
In general, semiconductor memories, which store information such as data or commands of programs, include a DRAM and a SRAM. A DRAM is a memory in which stored data may be read and other information may be stored. The DRAM allows information to be read therefrom and written thereon, but information stored in the DRAM is lost unless the information is periodically rewritten within a designated period while power is supplied. Although a DRAM needs to be refreshed in this way, it has a low price per memory cell and a high integration density, and is thus widely used as a high capacity memory.
A metal-oxide semiconductor field effect transistor (hereinafter, referred to as a “MOSFET”) is mainly used in memories, such as a DRAM, or logics. A MOSFET has a structure in which, after a gate oxide film, a polysilicon film, a gate metal, and a gate hard mask layer are deposited on a semiconductor substrate, gates are stacked thereon by a mask/etching process to form channels.
If the size of a semiconductor device having a general structure is reduced, channel length is also shortened. When the channel length of the device is shortened, a short channel effect and gate induced drain leakage (GIDL) can occur. In order to prevent such deterioration, it is necessary to increase gate channel length. However, increasing gate channel length causes problems, such as increasing gate resistance and deterioration of GIDL at a region where a gate and a source/drain region overlap with each other.